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Re: KA48 System Board Specification (Re: KA48 / VAXstation VLC cache question)

On Sun, 23 Aug 2015, Felix Deichmann wrote:

Am 20.08.2015 um 07:03 schrieb John Klos:
Any thoughts, anyone? How do we enable the cache on the KA48?

Got the "KA48 System Board Specification", KA48-0-DBF, as PDF (thanks to Antonio).
It has a chapter on cache and also its initialization, I hope it helps, John.



  Thnank you (and Antonio) VERY much.  I wish I had this 16 years ago :)

And yes, I had modified and enabled the cache enable originally, without any documenation. I can't remember any details and it doesn't look like there was much discussion on port-vax, so I'm guessing I had some private email exchanges (probably with Michael Kukat).

As I remember it, I started working on the 4000/VLC when the SCSI support was just getting added, and the cache enable code was disabled because it caused the system to hang or crash. Somehow I figured out that reading the PR_ICR register caused problems when the existing cache enable code was enabled, and not reading it made things work (and ran faster). From looking at the KA48 specifications, it sure doesn't look like the cache enable code was close to correct.

I think I had also found a DSNLink article that mentioned that on VMS, SYSLOA440 had code specific for the KA440 and KA48 systems, and I think I may tried to figure out what it was doing.

  Now I need to find some time to play with one of my VLC systems.


Michael L. Hitch                        mhitch%montana.edu@localhost
Operations Consulting,  Information Technology Center
Montana State University, Bozeman, MT     USA

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